PDF file: Annual Report 2002/2003 - Scottish Crop Research Institute

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Environment Figure 1 Disease progression (Rhynchosporium secalis) over successive times showing lessening effect of underlying 4 x 4 plot host (barley) planting pattern. depending upon the dispersal characteristics of the pathogen and its population structure. The structure of a crop canopy has the potential to influence the invasion, establishment and spread of insects through a field. Homogeneous canopy structures that have high levels of connectivity between stems and leaves may allow a rapid spread of herbivorous insects, thereby increasing the likelihood of pest populations reaching threshold levels. In addition, the dynamics between pests and their predators may be destabilised by this rapid population growth due to the lag in development of predator populations relative to their prey. If heterogeneity in canopy structure causes a reduction in the apparency of the plants to the herbivores, the plants have a refuge from insect attack and the population growth of the pest may be reduced. Introduction of sufficient heterogeneity in canopy architecture to impede the movement of herbivores without significantly affecting that of the predators may enhance the potential for natural biological control. 14 12 10 8 Number of species Weed herbivs Weed preds 4 Crop herbivs Crop preds 2 0 1 10 100 1000 10000 Number of individuals Figure 2 Figure showing greater diversity (steeper slope of the species-accumulation curve and higher intercept) in insect herbivores and predators associated with weed flora (heterogenous structure) compared to those insects associated with the crop vegetation (homogenous structure, OSR) Within-field heterogeneity is not only an important consideration for management of pest populations, but also for management to increase plant and invertebrate diversity. Increased canopy heterogeneity can result in greater diversity of associated herbivores and their natural enemies through the provision of a range of niches where direct competition for resources can be avoided. We have shown that the diversity of insects associated with the weed flora was greater than that associated with crop plants, and the diversity of predators was greater than that of their prey. In general, weed plants hosted up to ten times as many invertebrates per gram of plant material compared to the crop. Within-field plant diversity is therefore important for management of pests and to enhance diversity at higher trophic levels. This may be achieved either by allowing the development of the weed community to within acceptable limits according to the competitive ability of the weed population, or by creating a mixture of a range of different crop genotypes. Below ground, soil resources of water and nutrients are very patchily distributed. As much variation is often reported within the root system of a single plant as exists across a small field. Plants compete with their neighbours for these resources, and their effectiveness in doing so depends on their ability to grow a root into the resource patch, and the relative sink strength of the root for the resource. Hence, the interaction between root distribution, soil resource distribution, and the uptake efficiency determines the ability of plants to uptake water and nutrients, resulting in effects on the above ground canopy environment. We are studying both the genetic variation in root traits (Forster et al., 2003), and modelling the effect of root distribution and soil structure on uptake. There is potential to choose appropriate complementary root systems within a crop mixture to give a robust yield, whilst minimising nutrient loss. In the context of agriculture, compromises have to be reached between environmental or ecological considerations and the economics of food production. A yield of the quantity and quality required by end-users must be delivered in a timely and cost-effective way. However, the customer is not always right, and in some instances a compromise in some of their requirements may give them unforseen benefits in other areas whilst also satisfying the requirements of others further up and down in the supply train. We addressed an example of this in a previous article (Newton & Swanston, 1998) showing how better malt can be pro- 126
Environment duced from barley mixtures. Another example is illustrated by the difficulty of combining desirable traits within a single cultivar. The yield of alcohol obtainable from a sample of malt is determined by two factors, extract (the total soluble material) and fermentability (the proportion that yeast can convert into alcohol). Both factors are controlled by a number of genetic factors and, on one chromosome segment, desirable expressions for the two characters were shown to be linked in repulsion (Meyer et al., 2001). In this case, selection for optimal levels of extract could mean inheriting a gene that adversely affects fermentability whereas they can be combined in mixtures. This also illustrates the potential value of trait-associated markers in the the design of mixture. In conclusion, heterogeneity in canopy structure should be seen as an asset to be exploited to achieve practical, sustainable agriculture. As long as variation around an acceptable mean for the harvested product is comparatively small, end-users will not detect significant problems and if the buffering effects of mixtures reduce the environmental component of variation, acceptable levels of homogeneity should be readily obtainable. The reduction in requirements for pesticides from more balanced crop ecology, and the productivity gain from better resource utilisation, are self-evident benefits. References Meyer RC, Swanston, JS, Young GR, Lawrence PE, Bertie, A, Ritchie, J, Wilson A, Brosnan, J, Pearson, S, Bringhurst, T, Steele, G, Aldis, PR, Field, M, Jolliffe, T, Powell, W, Thomas, WTB, 2001. A genome-based approach to improving barley for the malting and distilling industries. Project Report No.264, Home-Grown Cereals Authority. Forster BP, Bengough G, Ellis RP, Thomas WTB, Clark S, Gordon D, El-Menaie H, Keith R, Waugh R, Hedley P, 2003. Genomics of the root-soil interface. Scottish Crop Research Institute Annual Report for 2001-2, pp. 154-154. Newton AC, Swanston JS, 1999. Cereal variety mixtures reducing inputs and improving yield and quality - why isn't everybody growing them? Scottish Crop Research Institute Annual Report for 1998/99, 55-59. 127
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Scottish Crop Research Institute ®
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The Scottish Crop Research Institut
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Contents Biomathematics and Statist
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Introduction upon the Commissioner
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Introduction ® Scottish Crop Resea
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Report of the Director John R. Hill
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Director’s Report tion from dismi
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Director’s Report paper A revised
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Director’s Report and the relatio
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Director’s Report Member States A
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Director’s Report US subsidies fr
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Director’s Report regions of the
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Director’s Report of silver and m
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Director’s Report tions. Obscenel
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Director’s Report participation.
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Director’s Report heads of state
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Director’s Report Philippines (2.
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Director’s Report Food Aid Famine
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Director’s Report adoption of unh
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Director’s Report economy propose
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Director’s Report (herbicides, in
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Director’s Report by a combinatio
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Director’s Report mended a study
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Director’s Report notes, bulletin
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Director’s Report research instit
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Director’s Report Ireland. Also i
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Director’s Report tats, most nota
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Director’s Report shares of total
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Director’s Report tonnes in 1999.
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Director’s Report Relative Import
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Director’s Report cheap food-stuf
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Director’s Report culturally-rela
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Director’s Report on large parts
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Director’s Report minimum input s
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Director’s Report organic farming
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Viruses - evolving organisms ? Viru
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Viruses - evolving organisms ? CLCu
Page 75 and 76: Viruses - evolving organisms ? a) b
Page 77 and 78: Barley Crop Development formation o
Page 79 and 80: Barley Crop Development Year Total
Page 81 and 82: Barley Crop Development on a year t
Page 83 and 84: GM herbicide-tolerant crops Some pe
Page 85 and 86: GM herbicide-tolerant crops and som
Page 87 and 88: GM herbicide-tolerant crops mitted
Page 89 and 90: GM herbicide-tolerant crops 12 Squi
Page 91 and 92: Mechanisms & Processes Peronospora
Page 93 and 94: Mechanisms & Processes Proteomic an
Page 95 and 96: Mechanisms & Processes High-through
Page 97 and 98: Mechanisms & Processes Studying pla
Page 99 and 100: Mechanisms & Processes Phytoene pea
Page 101 and 102: Mechanisms & Processes New discover
Page 103 and 104: Mechanisms & Processes in these cel
Page 105 and 106: Mechanisms & Processes d). This dat
Page 107 and 108: Genes to Products ic enzymes (use o
Page 109 and 110: Genes to Products Carotenogenesis i
Page 111 and 112: Genes to Products accumulation in s
Page 113 and 114: Genes to Products Retrotransposons
Page 115 and 116: SH43 SL03 SH44 SH12 B20 SL22 B47 B0
Page 117 and 118: Management of genes and organisms i
Page 119 and 120: Environment Functional diversity in
Page 121 and 122: Environment Plant root biomechanics
Page 123 and 124: Environment Microbial and microfaun
Page 125: Environment The role and importance
Page 129 and 130: Environment IOBC GMO Guidelines Pro
Page 131 and 132: Environment Mathematical modelling
Page 133 and 134: Biomathematics and Statistics Scotl
Page 135 and 136: Research services Analytical facili
Page 137 and 138: Research services Division of Finan
Page 139 and 140: Research services Information Techn
Page 141 and 142: Research services Estate, Glasshous
Page 143 and 144: Research services Engineering and M
Page 145 and 146: Research services MRS will: strengt
Page 147 and 148: Research services Health and Safety
Page 149 and 150: Publications Blok, V.C. 2002. Progr
Page 151 and 152: Publications Phenotype/genotype ass
Page 153 and 154: Publications for virus-transmitting
Page 155 and 156: Publications Muckenschnabel, I., Go
Page 157 and 158: Publications rich grassland. Procee
Page 159 and 160: Publications Woodford, J.A.T., Fent
Page 161 and 162: Statement of health & safety policy
Page 163 and 164: The Governing Body The Governing Bo
Page 165 and 166: The Governing Body development and
Page 167 and 168: Staff Theme 2 - Genes to Products T
Page 169 and 170: Staff Division of Finance and Admin
Page 171 and 172: Staff Resignations Name Unit Band M
Page 173 and 174: Staff Editorial Duties Name Positio
Page 175 and 176: Staff Name Position Committee or Or
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SCRI Research Programme 2002-2003 S
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Research Projects SCR/587/02 SCR/58
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Meteorological Records D. Petrie &
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List of Abbreviations AAB ACRE ADAS
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